Sash Windows
Supply only | Supply & Fit
At Colin’s Sash Windows, we design, supply and install bespoke sash windows across the UK. You can choose from uPVC, timber or thermally broken aluminium sash windows to match your property’s style and performance goals. Every sliding sash window is made to measure, tested for energy efficiency, and available with PAS 24 security options and conservation-friendly detailing.
Watch The Video Overview Of Our Sash Windows
In the following YouTube videos, we demonstrate our Spectus uPVC Sliding Sash
Windows, Ecoslide Sash Windows (also known as Victorian Sliders), and Legacy Sliding
Sash Windows in partnership with Spectus. Watch these videos to gain a complete
understanding of our sash windows.
What Are Sash Windows
A sash window is a vertically sliding window system made up of two glazed panels called sashes that move up and down within the outer frame.
At Colin’s Sash Windows, our sliding sash windows are available in single and double hung. Single Hung sash means only one sash moves upward and downward, while the double hung means both sashes will move. Each sash can slide to provide controlled ventilation and can be tilted inward for easy cleaning.
Why Choose Sash Windows
With Us?
Authentic detailing with modern performance
Double glazing to target U-values and noise reduction
Secure hardware options, including child safety restrictors
Colours, glazing bar layout, and sash horn detailing to suit period or contemporary homes
Professional survey, installation and aftercare with clear warranties
Materials of Double Glazed
Sash Windows
uPVC
Our uPVC sash windows are engineered for thermal insulation and low maintenance.
They feature multi-chambered frames, warm-edge double glazing, and tilt-in sashes for easy cleaning.
With A+ BFRC energy ratings, multi-point locks, and dual-colour or woodgrain finishes, they’re ideal for modern homes that want classic style with zero upkeep.
Timber
Our timber sash windows also interchangeably called “box sash windows” are built from engineered hardwood or softwood for long-lasting strength and heritage accuracy.
Each frame is factory finished with microporous paint coatings that allows the wood to breathe, reducing maintenance and preventing cracking.
Choose from nine standard colours or over 200 RAL options to match your property’s original character.
These windows are often specified for listed buildings and conservation areas where authenticity is essential, yet they still achieve A or B BFRC ratings.
Aluminium
For contemporary homes, our aluminium sash windows deliver slim sightlines, modern styling, and high strength.
Each frame is thermally broken for insulation and finished with durable powder coating.
They’re ideal for homeowners who prefer a modern steel-look design without compromising energy performance.
Our aluminium range meets PAS 24 for security and offers A to B energy efficiency ratings.
Performance That You Can Feel
U-Value
Superior thermal insulation
Solar Gain
Optimized natural light
Air Resistance
Minimal air leakage
All our sash windows are independently rated by the British Fenestration Rating Council (BFRC), the UK’s
trusted authority for window energy performance.
Typical ratings include A+ for uPVC, A or B for timber, and B for aluminium models. These ratings are
based on U-values, solar gain, and air leakage resistance.
Every product meets Building Regulations Part L and contributes to a warmer, more efficient home.
Double Glazing as Standard
All sash windows supplied by Colin’s Sash Windows are double glazed as standard. Each unit includes sealed glass panels with warm-edge spacers for improved thermal and acoustic performance. This combination helps achieve modern U-values while maintaining the traditional character of vertical sliders.
We do not retrofit double glazing into existing single glazed timber sashes, as doing so can compromise frame integrity and building regulation compliance. Instead, we provide a specialist Secondary Glazing system for homeowners who wish to retain their original single glazed windows but still improve insulation and noise control.
Our secondary glazing is a discreet internal frame fitted behind the existing window, reducing heat loss and outside noise without altering the building’s exterior, a popular option for listed buildings and conservation areas.
Energy and comfort
Target U-values that suit your specification and budget. Combine low-E coatings, gas fill and warm-edge spacers to improve efficiency and year-round comfort. Ask our team to balance energy, light and aesthetics for each room.
Energy Efficiency Comparison
| Window Type | Typical BFRC Rating | Typical U-Value (W/m²K) | Thermal Efficiency | Acoustic Performance | Best Suited For |
|---|---|---|---|---|---|
| uPVC Sash Windows | A to A+ | 1.2 – 1.4 | Excellent – multi-chamber frames and low-E double glazing reduce heat loss. | Very good – insulating frame and glazing. | Homeowners seeking high efficiency with minimal maintenance. |
| Timber Sash Windows | B to A | 1.3 – 1.6 | Very good – natural insulation and precision joinery maintain warmth. | Excellent – solid frames help dampen external noise. | Heritage properties and conservation areas where authenticity is key. |
| Aluminium Sash Windows | B (occasionally A) | 1.4 – 1.6 | Good – advanced thermal breaks improve insulation. | Good – rigid frame transmits slightly more sound. | Modern homes and commercial projects needing slim sightlines. |
Note: Ratings are based on BFRC certified simulations for double glazed sash windows. Performance can vary slightly depending on glazing specification, spacer type, and frame configuration.
Security and Safety
PAS 24 Security
All ranges can be specified with PAS 24 compliant hardware. Multi-point locking, reinforced keep plates, and laminated glass upgrades help resist forced entry.
Child Safety
Sash window restrictors can limit initial opening to support child safety without compromising everyday ventilation.
Design Options
Recreate period character with astragal or Georgian bars, sash horns and traditional hardware in brass, chrome or black finishes. Specify putty-line looks for timber, timber-alternative styling for uPVC, or slender aluminium for a contemporary take on vertical sliders.
Our uPVC sash windows are available in 8 solid or woodgrain colours, while timber frames come in 9 standard finishes or 200+ RAL shades.
Aluminium frames can be powder-coated in any modern colour to suit contemporary architecture.
Choose from obscure, decorative, diamond leaded, brilliant cut, or coloured glass to complement your home’s style. Our double glazing sash windows not only enhance appearance but also improve thermal insulation and noise reduction.
Our double glazing sash windows have a range of locks, handles, pulls, knobs, and horns. Among which most popular are:
- uPVC models use modern chrome or black hardware.
- Timber models can include polished brass or antique finishes for a period look.
- Aluminium models feature sleek, minimalist handles in brushed steel.
All hardware options are corrosion-resistant and security-tested to PAS 24 standards.
Calculate the Cost of Your Sash Windows
Get a fast, accurate estimate double glazed sash windows in just 60 seconds using our sash windows cost calculator. No sign-up, no obligation – simply enter your details and see your tailored price.
Made to Measure / Accreditations
Colin’s Sash Windows works only with accredited UK installation bodies, including FENSA, CERTASS, TrustMark,
and the Glass and Glazing Federation (GGF). Our uPVC sash windows and aluminum sash windows are Made in Britain
and include 10-year guarantees for materials, parts, and labour.
FENSA Certified
All installations are carried out by FENSA registered professionals. You receive a FENSA certificate confirming compliance with current Building Regulations for thermal performance and safety glazing.
CERTASS Approved
For certain projects, we also work with CERTASS approved partners who meet independent assessment standards for workmanship and competency.
TrustMark Registered
Our installers are TrustMark registered, demonstrating that we meet Government-endorsed standards of technical ability, customer care and financial protection.
PAS 24 Security
Windows can be specified and tested to PAS 24, verifying enhanced resistance to forced entry.
BS EN 14351-1
Every sash window meets the harmonised European standard for performance, covering air permeability, water tightness and structural strength.
GGF Membership
Our processes align with GGF best practice for glazing quality and consumer protection.
Building Regulations Part L and Part Q
All replacements comply with energy efficiency and security requirements for dwellings.
Insurance-backed guarantees
Colin’s Sash Windows works only with accredited UK installation bodies, including FENSA, CERTASS, TrustMark,
and the Glass and Glazing Federation (GGF). Our uPVC sash windows and aluminum sash windows are Made in Britain
and include 10-year guarantees for materials, parts, and labour.
Replacement Sash Windows
At Colin’s Sash Windows, we focus solely on period and heritage properties. Restoring old homes is not just about fitting new windows; it is about respecting their history, original craftsmanship, and architectural detail.
With more than 25 years of hands on experience, we do more than install new sashes. We specialise in authentic sash window replacement, carefully reproducing the look and proportions of the original units while upgrading performance. Every sash is crafted in a traditional style using modern, energy efficient materials, with A+ rated double glazing included as standard.
You’re protected, too:
✔️ 10-year guarantee on frames, hardware, and installation, backed by our own workmanship (not a third-party insurer)
✔️ 5 to 10 year guarantee on sealed units, because we engineered them in-house for total quality control.
Read more: Sash Windows Replacement Guide
Guarantee and Aftercare
10 Year Guarantee
Insurance-backed guarantee covering materials, parts, and labour
Glazing Protection
5 to 10 years warranties for performance and clarity
Full Aftercare
Complete support to ensure long-term reliability
Areas We Serve
Supply and installation are available nationwide in most areas across the UK. Request a quote with your
postcode and project details to confirm survey dates and lead times. We have the lowest leads times of 2-3 weeks
approx. for sash windows.
For delivery of our sash windows you can see the below image, in the green areas the delivery cost will be £36 and in yellow highlighted areas the delivery cost will be £120+ and for these areas please first talk to our sales team and then we will confirm you about delivery and with in red areas we don’t deliver our sash windows.
See What Our Customers Are Saying About Us
Frequently Asked Questions
Sash Windows Buying Guides
Ready to Get Started?
Design your bespoke sash windows with our team today. Share your sizes, material choice and any planning constraints. We will prepare a clear quotation and timeline, then book your survey.
Get in Touch At Once!
Feel free to call us on 01525 552131. Our friendly sales advisors will guide you through the ordering process and help you with anything regarding sash windows. Alternatively, don’t hesitate to write us via the contact form or directly to our email address sales@colinssashwindows.co.uk. Don’t waste your time and take advantage of the finest quotes throughout the UK and Ireland.
